I would like to have a list of the top 3 to 5 firms that provide
contract management, billing, invoicing, and W2 management for
independent contractors in technology (Java web development).  I am
not looking for a placement firm - I find my own customers, and would
simply like a firm to handle the contracts, billing, and my taxes. 
Research so far: http://www.mybizoffice.com would likely be on the
list - they do exactly what I'm looking for.  I'd just like some
additional options.  Good tip if you also explain each of the
companies rate structure (i.e. how they're paid).